Police in Dresden, Germany are on the hunt for at least two suspects after a break-in at the Grünes Gewölbe museum (also commonly known as the Green Vault) resulted in the theft of around 100 pieces of royal jewels and jewelry. The officials say that the items were of “immeasurable worth,” including a 648-carat sapphire that was once a royal gift from Russia’s Tsar Peter the Great. According to German media outlets, this theft represents the biggest incident of its kind since World War II.

Despite the heist’s apparent success and the high value of what was stolen, the theft itself seems a bit more like something you’d see from the Joker in Christopher Nolan’s Batman movies than the sort of stuff you’d get from the “Ocean’s 11” crew: Authorities were first alerted to the theft when a fire broke out in an electrical distribution box associated with the museum and which investigators now believe was set intentionally to disable the museum’s alarm system. Despite the lack of power, surveillance cameras continued to run, capturing footage of two men inside the museum.

There were security guards on duty at the time, but they reportedly called police rather than intervening, as that is the museum’s established procedure for this sort of crime. The guards were reportedly unarmed.

In order to gain access to the building, the two men only had to cut through a fence, remove an iron grill, and break a window. Once inside, they simply smashed through the cases holding three sets of jewels and jewelry — each set is made up of 37 individual pieces — and made off with them.